<?php
$dh = opendir('/dev/disk/by-uuid/');
while($file = readdir($dh)){
    if(is_link('/dev/disk/by-uuid/'.$file)){
        if( realpath('/dev/disk/by-uuid/'.$file) == '/dev/sda1'){
            echo 'Found uuid='.$file.PHP_EOL;
        }
    }
}